Elevator control system



Feb. 1967 D. J. ARBOGAST ETAL 3,302,531

ELEVATOR CONTROL SYSTEM Filed Aug. 5, 1964 I34 r gg 1 10 74 wn 1/ 10510s 1/; I35 Fla ,3 1/5 10/ I36 I27 '5 I92 Fm, @Wr WV/L- L iheirATTORNEYS United States Patent 3,392,531 ELEVATOR CONT RGL SYSTEM DuaneI. Arhogast, Olive Branch, and Lawrence F. Jaseph and Richard W. Green,Memphis, Tenn, assignors to Dover Corporation, Memphis, Tenn., acorporation of Delaware Filed Aug. 3, 1964, Ser. No. 386,829 Claims.(Cl. 91-446) This invention relates to a constant flow control deviceand more particularly, to a control means to be used in a hydraulicelevator system for maintaining a constant lowering speed of theelevator car regardless of load variation in the car.

Hydraulic elevators are commonly equipped with a jack cylinder and anelevator car plunger reciprocable therein. For raising the elevator car,hydraulic fluid is supplied under pressure to the jack cylinder by meansof a pump, and for lowering the car, the hydraulic fluid, which is underpressure due to the weight of the plunger and the loaded elevator carsupported thereby, is con trollably returned from the jack cylinder to areservoir through a lowering valve. In the past there has beenconsiderable variation in the speed of descent of the elevator car inaccordance with the load therein, inas' much as heavier loads force thehydraulic fluid through the lowering valve at a higher volumetric rateof flow. Furthermore, variations in speed of descent prevent theelevator car from stopping consistently level with the desired landing.

In Patent Nos. 3,020,891 and 3,020,892, both issued February 13, 1962,means are disclosed for overcoming the above-mentioned difficulties byproviding two regulated speeds of descent, a normal lowering speed and arelatively slow levelling speed, the latter being used as the elevatorcar approaches a floor at which it is to stop. Both patents disclose theuse of two principal valve assemblies: a controlled valve to open to oneof two fixed positions, corresponding to the two speeds of descent, tothrottle the flow of hydraulic fluid therethrough and cause a pressuredrop which varies with the rate of the flow dependent upon the load ofthe elevator car; and a regulator valve controlled by this pressure dropto open or close to the degree necessary to maintain the desired flow.In both patents it is the controlled valve which closes to form afluid-tight seal when no flow is desired, but the regulator valve, whichsenses the pressure upstream of the controlled valves, must also havezero leakage under steady state conditions. Furthermore, inasmuch as thefixed positions of the controlled valve are adjustable, this valve is ofrelatively complex construc tion.

The present invention overcomes the disadvantages of the above-mentionedpatents by providing a controlled valve which never closes, but onlyassumes one of two fixed positions corresponding to the two speeds ofdescent. It is only the regulator valve, which is located downstream ofthe controlled valve, which makes a fluidtight seal. This permits thecontrolled valve to be of very simplified construction.

The invention is more fully explained in the following detaileddescription of an exemplary embodiment, this description beingillustrated by the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a hydraulic elevator system,including the control means of the present invention;

FIG. 2 is an enlarged sectional view of the control means of FIG. 1taken on a vertical plane through the middle thereof; and

FIG. 3 is a sectional view of an alternative embodiment of one of thecontrol elements of FIG. 2.

3,302,531 Patented Feb. 7, 1967 FIG. 1 illustrates a typical hydraulicelevator system with which a lowering control means 10 is adapted to beused in accordance with the present invention. An eleva tor car 11 issupported by a plunger 12 reciprocably mounted in a hydraulic jackcylinder 13, suitable packing means (not shown) being provided at thetop of the cylinder 13 to prevent the escape of hydraulic fluid frombetween the cylinder 13 and the plunger 12. A conduit 14 communicatesthe interior of the jack cylinder 13 directly with the control means 10and through a suitable check valve 16 with a hydraulicpump 15. The pumpis driven by a prime mover 17 such as an electric motor or the like. Adischarge conduit 18 connects the control means 10 with a reservoir 19.Hydraulic fluid may be supplied to the pump from the reservoir 19through a conduit 20.

When the elevator car 11 is to be raised, hydraulic fluid is taken fromthe reservoir 19 by the pump 15 and forced through the check valve 16and the conduit 14 to the jack cylinder 13, the lowering control means10 being sealed against flow therethrough. When the elevator car is tobe lowered, the hydraulic fluid in the jack cylinder 13 is permitted toflow through the control means 10 to the reservoir 19. As will beexplained in detail hereinafter, the control means 10 may be controlledto permit the elevator car 11 to descend at a predetermined normallowering speed or a predetermined relatively low levelling speed.Moreover, the control means 10 may be sealed against fluid flowtherethrough to bring the elevator car to a complete stop.

Turning now to FIG. 2, the lowering control means 10 includes a casing21 which forms an inlet chamber 22, an intermediate chamber 23, and adischarge chamber 24. There is an inlet port 25 by which the inletchamber 22 may be connected to the conduit 14, and a discharge port 26by which the discharge chamber 24 may be connected to the dischargeconduit 18.

A speed control valve 27 includes a cylindrical plug 28 which isslidably mounted in and in close fitting engagement with port orpassageway 29 between the inlet chamber 22 and the intermediate chamber23. The plug 28 is provided with a plurality of shaped ports 30extending from the lateral surface of the plug to its end surfaceexposed to the intermediate chamber 23, whereby axial movement of theplug 28 varies the size of the effective passageway between the inletchamber 22 and the intermediate chamber 23. Connected to the plug 28 bya stem 31 is a piston 32 which is slidably mounted in a bore 33 formedin the casing 21. The surface of the piston 32 remote from the plug 28is exposed to a chamber 3-, which is closed by a cap 35, a gasket 36 anda plurality of screws 37 providing a fluid-tight seal therefor. Acompression spring 38 biases the valve 27 toward the closed position, orto the left as viewed in FIG. 2. An adjustable stop screw 39, mounted inthe cap 35, limits the travel of the valve 27 in the opening direction.Another adjustable stop screw mounted in the casing 21 limits the travelof the valve 27 in the closing direction. The stop screws 39 and 40 arelocked by the nuts 41 and 42, respectively, and are secured againstfluid leakage by the gaskets 43 and 44 and cap nuts 45 and 46,respectively.

A regulator valve 47 includes a cylindrical plug 43 which is slidablymounted in a port or passageway 49 between the intermediate chamber 23and the discharge chamber 24. The plug 43 is provided with a pluralityof shaped ports 50 extending between the lateral surface of the plug andits end surface exposed to the discharge chamber 24. The port 49 isbeveled to form a seat at 51, and the plug 48 is formed with a laterallyextending flange 52 adapted to cooperate with the seat 51 to seal theport 49 against fluid flow from the intermediate chamber 23 to thedischarge chamber 24. Connected to the plug 48 by a stem 53 is a piston54 slidably mounted in and 1n sealed relation to a passageway 55 betweenthe inlet chamber 22 and the intermediate chamber 23. Coaxial with thepassageway 55 is an opening 56 formed in the casing 21. The opening 56is closed by a plate 57, a gasket 58 and a plurality of screws 59insuring a fluid-tightseal. A stop 60, which may be adjustable ifdesired, limits movement of the valve 47 in the opening direction (tothe right as viewed in FIG. 2) when engaged by a recessed surface 61 inthe piston 54. Access may be had to the valve 47 by removing the plate57.

A chamber 62 communicates with the discharge chamber 24 through a bore63 which is in spaced relation to the port 49. Slidably mounted in thebore 63 is a piston 64 having a boss 65 extending into the dischargechamber 24 and adapted to bear against the plug 48. The side of thepiston 64 exposed to the chamber 62 is recessed at 65a to seat one endof a compression spring 66, which is preferably of a low rate, orlimber. The chamber 62 is closed by a cover 67, a gasket (not shown) anda plurality of screws 68 insuring a fluid-tight seal. An adjusting screw69, mounted in the cover 67, supports a spring carrier 70 by means ofwhich the spring 66 is maintained in compression. The force of thespring 66 acting through the piston 64 urges the valve 47 in the openingdirection. The adjusting screw 69 is locked by anut 71 and securedagainst leakage by a gasket 72 and a capiiut 73.

The speed control valve 27 may assume one of two fixed positions, as itabuts the stop screw 39 or 40, to provide two degrees of opening betweenthe inlet chamber 22 and the intermediate chamber 23 to provide thenormal lowering speed descent or the relatively slow levelling speeddescent of the elevator car 11, respectively. The position taken'by thevalve 27 is determined by the direc tion of the resultant force thereonof the forces produced by the pressures in the chambers 22, 23 and 34 aswell as by the compression spring 38.

The valve 47 may be seated as illustrated in FIG. 2 to prevent the flowof hydraulic fluid through the control means 10, when the closing forcesproduced by the pressures in the chambers 22 and 23 exceed the openingforces produced by the compression spring 66 and the pressure in thechamber 62; or it may open to the degree necessary to balance theopening force provided by the compression spring 66 and the closingforce due to the pressure differential in the chambers 22 and 23, aswill be explained in detail hereinafter.

The desired positions for the valves 27 and 47 are selected by means ofcontrol elements or devices 74 and 75, respectively. Briefly, to placethe valve 27 in the position of minimum opening as illustrated in FIG. 2corresponding to elevator levelling speed, the control device 74connects the chamber 34 with the inlet chamber 22. With the valve 47open to permit fluid flow through the ports 30, the forces urging thevalve 27 in the closing direction, resulting from the relatively highpressure in the chambers 22 and 34 as well as from the compressionspring 38, exceed the opening force on the valve 27 resulting from therelatively low pressure in the chamber 23. When the valve 47 is in theclosed position, the pressures in the chambers 22 and 23 are the sameand the spring 38 tends to keep the valve 27 in the mini-mum openingposition. The control device 74 causes the valve 27 to shift to aposition against the adjusting screw 39, corresponding to the normallowering speed of the elevator car 11, by connecting the chamber 34 withthe discharge chamber 24. Under these conditions the opening force onthe valve 27 resulting from the relatively high pressure in the chamber23 exceeds the closing forces resulting from the relatively low pressurein the chamber 34 and from the compression spring 38.

The control device 75 normally causes the valve 47 to assume the closedposition illustrated in FIG. 2 by connecting the chamber 62 with thedischarge chamber 24.

The closing force on the valve 47 due to the relatively i pressure inthe chambers 22 and 23 exceeds the openin forces due to the relativelylow pressure in the chamber 62 and due to the compression spring 66- T0Permlt the elevator car 11 to descend, the control device 75 connectsthe chamber 62 with the intermediate chamber 23. Under these conditionsthe valve 47 opens u t the Opening force due to the spring 66 isbalance-d by the closing force d to the pressure differential betweenthe chambers 22 and 23, inasmuch as there is zero resultant static forceon the plug 48 and the piston 64 resulting from the pressures in thechambers 23, 24 and 62, notwithstanding the fact that, when there isflow through the control means 10, there will be dynamic forces on theplug 48 and the piston 64 in one direction or the other, which may berendered insignificant by properly shaping the ports 50.

The control device 75 comprises a body 76 having two concentric chambers77 and 78 of diiferent diameter to receive a spool valve 79, the largerend of Which forms a piston 80 slidably received in the chamber 77 andthe smaller end of which is formed with two lands 81 and 82 slidablyfitted in the chamber 78. An intermediate portion of the spool valve 79is beveled to form a seating surface 83 adapted to make a fluid-tightseal between the chambers 77 and 78. The valve 79 is urged to its closedposition illustrated in FIG. 2 by a compression spring 84. Hydraulicfluid may flow from the chamber 78 through a port 85 past an adjustableneedle valve 86 through a conduit 87 to the chamber 62. Return flow fromthe chamber 62 may flow through the conduit 87 past a ball valve 88 tothe port 85. Direct communication is provided from the chamber 78through a port 89 to a conduit 90, while a port '91 in this chamber 78leads past an adjustable needle valve 92 to the conduit 90. The conduitcommunicates through a conduit 93 with the discharge chamber 24. Theports 89 and 91 are on opposite sides of the land 81 when the valve 79is in the position illustrated in FIG. 2. A port 94 in the end of thechamber 77 adjacent the chamber 78 communicates with the intermediatechamber 23 by a conduit 95. A port 96 at the opposite end of the chamber77 communicates with the conduit through a restricted orifice 97, and isconnected by a passage 98 past a solenoid valve means 100 having aplunger 99 to the conduit 93 leading to the discharge chamber 24.

The control device 74 includes a body 101 having two concentric chambers102 and 103 of diflerent diameter to receive a spool valve 104, thesmall end of which is formed with a cylindrical land 105 which isreceived within the chamber 103. Projecting from the land 105 is abeveled surface 106 which is adapted to make a fluidtight seal at a port107 in the chamber 103. The other end of the spool 104 is formed into apiston 108 which is slidably fitted in the chamber 102. A compressionspring 109 urges the spool valve 104 to the closed position. The port107 communicates past an adjustable needle valve 110 with the conduit 93and then to the discharge chamber 24, while another port 111 in thechamber 103 communicates through the conduit 112 to the chamber 34. Aport 113 in the end of the chamber 102 remote from the chamber 103communicates by a passage 114 past a solenoid valve means 116 having aplunger to the conduit 93 leading to the discharge chamber 24. The otherend of the chamber 102 communieates through a restricted orifice 117 tothe passage 114, and by a passage 118 past an adjustable needle valve119 through a conduit 119a to the inlet chamber 22.

FIG. 3 illustrates a control device 120 which may be susbtituted for thecontrol device 74. A body 121 is formed with a chamber 122 within whichis slidably mounted a spool valve 123. The spool valve 123 is formedwith two lands 124 and 125 and has a beveled surface 126 adapted to makea fluid-tight seal at a port 127 in one end of the chamber 122, the port127 communicating with the conduit 93. A compression spring 128 biasesthe valve 123 to the open position. Two ports 129 and 130 in the lateralwall of the chamber 122 communicate directly with the conduit 119a, andpast an adjustable needle valve 131 to the conduit 112, respectively. Aport 132 in the end of the chamber 122 remote from the port 127communicates with a passage 133 which leads past a solenoid valve means135 having a plunger 134 to the conduit 93, and a restricted orifice 136in the lateral wall of the chamber 122 communicates this chamber withthe passage 133.

In operation, when the elevator car 11 is to be lowered, both solenoidvalve means 116 and 100 are energized by any suitable control means wellknown in the art. The plunger 115 is lifted from its seat relievingpressure from the passage 114 to the discharge chamber 24, whereby thepressure to the right of the piston 108 (as viewed in FIG. 2) becomesthat of the discharge chamber. (When the plunger 115 is in its closedposition as illustrated, the pressure in the passage 114 stabilizes bymeans of the restricted orifice 117 at the pressure in the chambers 22and 34.) Inasmuch as the pressure to the left of the piston 168 (whichis larger than the land 105), which has stabilized at the pressure ofthe inlet chamber 22 through the conduits 118 and 119a, is sufl'icientto overcome the bias of the spring 109, the spool valve 104 moves to theright and is unseated. As the land 105 moves past the port 111, theconduit 118 is cut off from the conduit 112, which may then drain thechamber 34 through the conduit 93 to the discharge chamber 24. Inasmuchas the cross-sectional area of the piston 32 is at least as large asthat of the plug 28, and the pressure in the chamber 23 is that of thechamber 22 (the valve 47 being closed) and is always greater than thepressure in the discharge chamber 24 (which is also that of the chamber34 after the solenoid valve means 116 has been energized), the netopening force on the speed control valve 27 overcomes the bias of thespring 38 and causes the valve 27 to open until the adjustable stop 39is encountered.

When the solenoid valve means 100 is energized, the plunger 99 is liftedfrom its seat, whereby the pressure to the right of the piston 80 (asviewed in FIG. 2) is relieved to the discharge chamber 24. Inasmuch asthe port 94 delivers pressure fluid from the chamber 23 by the conduit95 to the left of the piston 80, the bias of the spring 84 is overcomeand the spool valve 79 is unseated. The land 81 cuts off the port 91from the port 85, while the land 82 is lifted out of its bore to connectthe port 85 with the port 94, where-by the pressure fluid from thechamber 23 is permitted to flow through the port 85 past the adjustableneedle valve 86 and through the conduit 87 to the chamber 62.

When the alternate control device 120 is used, the plunger 134 is causedto open, whereupon the fluid pressures on each end of the spool valve123 are balanced. Under these conditions the spring 128 drives the valve123 to the right (as viewed in FIG. 3), whereby communication betweenthe ports 129 and 130 is cut off by the land 125. The pressure fluid inthe chamber 34 is then permitted to drain through the conduit 112 andflow past the adjustable needle valve 131 and through the port 127 andconduit 93 to the discharge chamber 24.

After the chamber 23 has been connected with the chamber 62 by thecontrol device 75, the forces on the valve 47 due to the pressures inthe chambers 22, 23, 24 and 62 are balanced, and so the force exerted bythe spring 66 lifts the valve 47 off its seat at a rate determined bythe flow of hydraulic fluid past the adjustable needle valve 86. As thevalve 47 opens, fluid flows from the chamber 22 through the ports 30 inthe plug 28 to the chamber 23, and then through the ports 50 in the plug48 to the discharge chamber 24 and on to the reservoir 19.

The rate of flow through the lowering control means increases as thevalves 27 and 47 are opening, and the desired rate of flow correspondingto the normal lowering speed of the elevator car is attained after thevalve 27 reaches the adjustable stop 39. This rate of flow causes adefinite pressure differential between the chambers 22 and 23 as thefluid passes through the effective aperture caused by the ported plug 28in the port 29. Inasmuch as the forces on the plug 48 and the piston 64due to the pressure in the chambers 23 and 62 are balanced, theresultant force on the piston 54 due to the pressure differentialbetween the chambers 22 and 23 opposes the bias of the spring 66, andthe spring is adjusted by the adjusting screw 69 so that these twoforces are balanced at the desired rate of flow.

This desired flow is maintained regardles of the actual value of thepressure in the chamber 22 due to the elevator load within wide limits.An increase in elevator load would tend to increase the fluid flowthrough the lowering control means 10 if the effective aperture throughthe port 49 remained constant, however the increased pressure in thechamber 22 caused by the increased load causes the valve 47 to move inits closing direction. This decreases the effective aperture through theport 49 and therefore the fluid flow therethrough until the pressure inthe chamber 23 rises to a value diifering from that in the chamber 22 bythe desired pressure diflerential, under which conditions the adjustedflow through the control means 10 is attained. Similarly, a decreasedload in the elevator car reduces the pressure in the chamber 22,whereupon the valve 47 moves in the opening direction to maintain thesame fluid flow rate under the reduced pressure conditions.

As the valve 47 opens, the spring 66 extends and exerts a smaller force.This would tend to reduce the pressure differential across the piston 54and thereby produce a smaller flow than desired, were it not for theshaping of the ports 50 as indicated in FIG. 2 to compensate for thespring rate of the spring 66, and also the arrangement of the ports 50in the plug 48, whereby the fluid passing through these ports isdirected against the piston 64. The impact of the fluid on the piston 64is less under wide open, low pressure flow than under restricted, highpressure flow of equal Volume, thereby compensating for the change ofspring force with extension. Furthermore, the spring 66 preferably has alow rate, so that there is relatively slight change of force withchanging length over the range employed.

When the elevator car 11 approaches a landing, it is desirable to reduceits speed to a low value in a smooth and controlled manner. Suitablecontrol means well known in the art de-energize the solenoid valve means116 at a proper point in the travel of the car 11 to so reduce itsspeed. The plunger 115 drops to its seat, preventing further escape offluid from the passage 114. Fluid under pressure entering through theconduits 119a and 113 passes through the restricted orifice 117 andthrough the port 113, whereu on the spool valve 104 is driven to itsseating position. The chamber 34 is now connected to the inlet chamber22 through the conduits 112, 118 and 1191!, so that the speed controlvalve 27 is driven in its closing direction at a rate determined by thespeed of fluid flow past the adjustable needle valve 119 until the stop40 is met.

The gradually decreasing effective aperture through the port 29 causesan increased pressure drop between the chambers 22 and 23. The force ofthis increased pressure differential acting on the valve 47 exceeds thatsupplied by the spring 66, and therefore the valve 47 is moved towardits closed position at a relatively rapid rate, since fluid may leavethe chamber 62 by way of the conduit 87, ball check valve 88, ports and94, and conduit to the chamber 23. It is evident that there being norestriction in the path just described, the valve 47 may closely followthe movement of the valve 27 and thereby limit the fall of pressure inthe chamber 23. This fall of pressure cannot be faster than the valve 27can move, and the movement of this valve 27 is limited by the adjustmentof the needle valves 111 and 119. When the speed control valve 27 isagainst the stop 40, the pressure drop for which the valve 47 isbalanced will be obtained at a relatively small fluid flow rate throughthe plug 28, perhaps only th the rate attained when both solenoid valvemeans 100 and 116 are energized, for example.

As the valve 27 closes, the pressure differential between the chambers22 and 23 is increased, so that the valve 47 is urged toward its closedposition until the force on this valve 47 due to the pressuredifferential balances the force supplied by the spring 66. The valve 47is balanced to provide a smaller effective aperture through the port 49,and the spring 66 is compressed to provide a slightly greater force thanobtained under the conditions of normal lowering speed descent discussedabove, but this spring characteristic is compensated by the manner inwhich the ports 50 are shaped and by the impact of the fluid dischargedby these ports 50 on the piston 64.

The relatively slow levelling speed descent is regulated to be constantin the same way that the normal lowering speed descent is regulated,i.e. changes of load in the elevator car 11 cause corresponding changesin the effective aperture through the port 49, whereby a constantpressure differential between the chambers 22 and 23 is maintainedproducing a constant fluid flow through the fixed effective aperturecaused by the plug 28 in the port 29.

If the control device 120 is substituted for the control device 74, thede-energiz ation of the solenoid valve means 135 permits the plunger 134to seat, preventing the drain ing of fluid from the passage 133. Highpressure fluid from the inlet chamber 22 enters the chamber 133 throughthe conduit 119a and the restricted orifice 136. The fluid flows throughthe port 132 and drives the spool valve 123 against the spring 128 untilthe beveled surface 126 seats to seal the port 127. The ports 129 and130 are now connected so that the pressure fluid from the chamber 22 maypass through the conduits 119a and 112 to the chamber 34, whereupon thevalve 27 is driven in its closed direction at a speed determined by therate of fluid flow past the adjustable needle valve 131.

When the elevator car is within a fraction of an inch of its desiredstopping level, well known control means de-energize the solenoid valvemeans 100 permitting the plunger 99 to seat and prevent the escape offluid from the passage 98. Pressure fluid from the chamber 23 passesthrough the conduit 95 and the restricted orifice 97 to the port 96 andacts with the spring 84 to urge the spool valve 79 to its seatedposition. The chamber 62 is now cut off from the intermediate chamber 23and is connected to the outlet chamber 24 through the conduits 87, 9t}and 93. The valve 47 is now unbalanced and will close promptly inasmuchas the forces due to the pressures in the chambers 22 and 23 exceed theforce supplied by the spring 66. The valve 47 is therefore fully butgently closed at a rate determined by the adjustment of the needle valve92, and the elevator car is brought to rest in the fraction of an inchof travel desired.

The lowering control means 10 according to the present inventionprovides two speeds of descent, both of which are regulated to beconstant regardless of the load in the elevator car 11. The speedcontrol valve 27 is not required to make a fluid-tight seal and assumesone of only two stable positions corresponding to the two speeds ofdescent. Moreover, should there be any leakage between the piston 54 andthe port 55, there will be no slippage of the elevator car 11, inasmuchas the plug 43 makes a fluid-tight sea-l in the port 49 under steadystate conditions. There can also be no leakage through the controldevices 74, 75 and 120, since the plungers 115, 99 and 134,respectively, and the beveled surfaces 106, 83 and 126, respectively,all make fluidtight seals which are unattainable with ordinary spoolvalves.

While specific exemplary embodiments of the invention have been shownand described, it will be understood that various substitutions, changesand modifications in the form and details of the illustrated embodimentsand their manner of operation may be made by those skilled in the artwithout departing from the spirit and scope of the invention. Forexample, the adjustable needle valve 110 could be omitted and theinitial acceleration of the elevator car governed solely by the Openingrate of the valve 47, i.e. by the adjustable needle valve 86. Also thebore 63 could be made somewhat larger in cross-sectional area than theport 49, suitable adjustment being made in the shape of the ports 50 andin the force supplied by the spring 66 as necessary. Therefore, theinvention is not deemed to be limited except as defined by the dependingclaims.

We claim:

1. A constant flow control device, comprising a valve casing includingan inlet chamber, an intermediate chamber and a discharge chamber, saidinlet chamber being in continuous communication with said intermediatechamber through a first passageway of variable effective size and saidintermediate chamber being in selectively controllable intermittentcommunication with said discharge chamber through a second passageway,an inlet port in said inlet chamber adapted to be connected to a sourceof fluid under pressure, a discharge port in said discharge chamberadapted to be connected to a discharge conduit, control valve meansdisposed in said first passageway for controlling the variable effectivesize thereof, said control valve means having a plurality of operativepositions corresponding to a plurality of different predetermined ratesof fluid flow through said first passageway, regulator valve meansdisposed in said second passageway for regulating fluid flow therein,said regulator valve means including pressure responsive meansassociated therewith adapted to selectively seal said second passagewayagainst fluid from said intermediate chamber to said discharge chamberto interrupt communication therebetween, and positioning means coupledto said regulator valve means and sensitive to the pressure differentialbetween said inlet and intermediate chambers for adjusting saidregulator valve means so that the fluid flow through said control valvemeans is substantially constant for said plurality of operativepositions under varying pressure of the fluid supplied to said inletchamber.

2. A constant flow control device, comprising a valve casing includingan inlet chamber, an intermediate cham ber and a discharge chamber, saidinlet chamber being in continuous communication with said intermediatechamber through a first apassageway of variable effective size and saidintermediate chamber being in selectively controllable intermittentcommunication with said discharge chamber through a second passageway,an inlet port in said inlet chamber adapted to be connected to a sourceof fluid under pressure, a discharge port in said discharge chamberadapted to be connected to a discharge conduit, control valve meansdisposed in said first passageway for controlling the variable effectivesize thereof, said control valve means having a plurality of operativepositions corresponding to a plurality of different predetermined ratesof fluid flow through said first passageway regulator valve meansdisposed in said second passageway for regulating fluid flow therein,said regulator valve means including pressure responsive meansassociated therewith adapted to selectively seal said second passagewayagainst fluid flow from said intermediate chamber to said dischargechamber to interrupt communication therebetween, positioning meanscoupled to said regulator valve means and sensitive to the pressuredilferential between said inlet and intermediate chambers for adjustingsaid regulator valve means so that the fluid flow through said controlvalve means is substantially constant for said plurality of operativepositions under varying pressure of the fluid supplied to said inletchamber, and first control means for selectively adjusting said controlvalve means to one of said plurality of operative positions.

3. A constant speed lowering control means for 'a hydraulic elevatorsystem including a jack cylinder containing hydraulic fiuid, an elevatorcar plunger reciprocable therein, a pumpand a reservoir, comprising avalve casing including an inlet chamber, an intermediate cham ber and adischarge chamber, said inlet chamber being in continuous communicationwith said intermediate chamber through a first passageway of variableeffective size and said intermediate chamber being in selectivelycontrollable intermittent communication with said discharge chamberthrough a second passageway, an inlet port in said chamber adapted to beconnected to the jack cylinder of a hydraulic elevator system with whichthe control means is adapted to be used, a discharge port in saiddischarge chamber adapted to be connected to the reservoir of ahydraulic elevator system, selectively operable speed control valvemeans disposed in said first passageway for controlling the variableeffective size thereof, said control valve means having two operativepositions corresponding to two lowering speeds of an elevator carplunger with which the control means is adapted to be used, regulatorvalve means disposed in said second passageway for regulating fluid flowtherein, said regulator valve means including pressure responsive meansassociated therewith adapted to selectively seal said second passagewayagainst hydraulic fluid flow from said intermediate chamber to saiddischarge chamber to interrupt communication therebetween, andpositioning means coupled to said regulator valve means and sensitive tothe pressure diiferential between said inlet and intermediate chambersfor adjusting said regulator valve means to provide a pressure in saidintermediate chamber such that the pressure differential between saidinlet and intermediate chambers remains substantially constant undervarying pressure conditions in said inlet chamber.

4. A constant speed lowering control means for a hydraulic elevatorsystem including a jack cylinder containing hydraulic fluid, an elevatorcar plunger reciprocable therein, a pump and a reservoir, comprising avalve casing including an inlet chamber, an intermediate chamber and adischarge chamber, said inlet chamber being in continuous communicationwith said intermediate chamber through a first passageway and ofvariable effective size and said intermediate chamber being inselectively controllable intermittent communication with said dischargechamber through 'a second passageway, an inlet port in said inletchamber adapted to be connected to the jack cylinder of a hydraulicelevator system with which the control means is adapted to be used, adischarge port in said discharge chamber adapted to be connected to thereservoir of 'a hydraulic elevator system, selectively operable speedcontrol valve means disposed in said first passageway for controllingthe variable effective size thereof, said control valve means having twooperative positions corresponding to two lowering speeds of an elevatorcar plunger with which the control means is adapted to be used,regulator valve means disposed in said second passageway for regulatingfluid flow therein, said regulator valve means including pressureresponsive means associated therewith adapted to selectively seal saidsecond passageway against hydraulic fluid flow from said intermediatechamber to said discharge chamber to interrupt communicationtherebetween, positioning means coupled to said regulator valve meansand sensitive to the pressure differential between said inlet andintermediate chambers for adjusting said regulator valve means toprovide a pressure in said intermediate chamber such that the pressuredifferential between said inlet and intermediate chambers remainssubstantially constant under varying pressure conditions in said inletchamber, and first control means for selectively moving said speedcontrol valve means between said two operative positions.

5. A constant speed lowering control means for a hydraulic elevatorsystem including a jack cylinder containing hydraulic fluid, an elevatorcar plunger reciprocable therein, a pump and a reservoir, comprising avalve casing including an inlet chamber, an intermediate chamber and adischarge chamber, said inlet chamber being in continuous communicationwith said intermediate chamber through a first passageway of variableeffective size and said intermediate chamber being in selectivelycontrollable intermittent communication with said discharge chamberthrough a second passageway, an inlet port in said inlet chamber adaptedto be connected to the jack cylinder of a hydraulic elevator system withwhich the control means is adapted to be used, a discharge port in saiddischarge chamber adapted to be connected to the reservoir of ahydraulic elevator system, selectively operable speed control valvemeans disposed in said first passageway for controlling the variableetfective size thereof, said control valve means having two operativepositions corresponding to two lowering speeds of an elevator carplunger with which the control means is adapted to be used, regulatorvalve means disposed in said second passageway for regulating fluid flowtherein and for selectively sealing said second passageway againsthydraulic fluid flow from said intermediate chamber to said dischargechamber to interrupt communication therebetween, positioning meanscoupled to said regulator valve means and sensitive to the pressuredifferential between said inlet and intermediate chambers for adjustingsaid regulator valve means to provide a pressure in said intermediatechamber such that the pressure diiferential between said inlet andintermediate chambers remains substantially constant under varyingpressure conditions in said inlet chamber, means forming a first chamberin communication with said inlet chamber through a first bore, saidfirst bore being in spaced relation to said first passageway, a firstpiston slidably received in said first bore and connected to said speedcontrol valve means, first adjustable stop means for limiting movementof said speed control valve means in a direction to increase thelowering speed of said elevator car plunger, said adjustable stop meansfor limiting movement of said speed control valve means in a directionto decrease the lowering speed of said elevator car plunger, firstspring-actuated biasing means urging said speed control valve means in adirection to decrease the lowering speed of said elevator car plunger,and first control means for selectively moving said speed control valvemeans between said two operative positions.

6. The constant speed lowering control means of claim 5, wherein saidfirst control means includes means for selectively communicating saidfirst chamber with said inlet chamber and said discharge chamber.

7. A constant speed lowering control means for a hydraulic elevatorsystem including a jack cylinder containing hydraulic fluid, an elevatorcar plunger reciprocable therein, a pump and a reservoir, comprising avalve casing including an inlet chamber, an intermediate chamber and adischarge chamber, said inlet chamber being in continuous communicationwith said intermediate chamber through a first passageway of variableeffective size and said intermediate chamber being in selectivelycontrollable intermittent communication with said discharge chamberthrough a second passageway, an inlet port in said inlet chamber adaptedto be connected to the jack cylinder of a hydraulic elevator system withwhich the control means is adapted to be used, a discharge port in saiddischarge chamber adapted to be connected to the reservoir of ahydraulic elevator system, selectively operable speed control valvemeans disposed in said first passageway for controlling the variableelfective size thereof, said control valve means having two operativepositions corresponding to two lowering speeds of an elevator carplunger with which the control means is adapted to be used, regulatorvalve means disposed in said second passageway for regulating fluid flowtherein and for selectively sealing said second passageway againsthydraulic fiuid flow from said intermediate chamber to said dischargechamber to interrupt communication therebetween, positioning meanscoupled to said regulator valve means and sensitive to the pressuredifferential between said inlet and intermediate chambers for adjustingsaid regulator valve means to provide a pressure in said intermediatechamber such that the pressure differential between said inlet andintermediate chambers remains substantially constant under varyingpressure conditiorrs in said inlet chamber, wherein said secondpassageway in cludes a beveled seat on the intermediate chamber sidethereof, and said regulator valve means includes a flange portionadapted to cooperate with said beveled seat to seal said secondpassageway against hydraulic fluid flow from said intermediate chamberto said discharge chamber.

8. The constant speed lowering control means of claim 7, wherein saidpressure responsive means includes means forming a second chamber incommunication with said discharge chamber through a second bore, saidsecond bore being in spaced relation to said second passageway, a secondpiston slidably received in said second bore and coupled with saidregulator valve means, second springactuated biasing means urging saidregulator valve means in a direction to unseal said second passageway,and sec ond control means for moving said regulator valve means toselectively seal and unse al said second passageway.

9. The constant speed lowering control means of claim 12 8, wherein saidsecond control means includes means for selectively communicating saidsecond chamber with said intermediate chamber and said dischargechamber.

10. The constant speed lowering control means of claim 8, wherein saidpositioning means comprises a third bore between said inlet andintermediate chambers and in spaced relation with said secondpassageway, and a third piston having two opposite surfaces, slidablydisposed in said third bore and rigidly connected to said regulatorvalve means, one of said two opposite surfaces being exposed to saidinlet chamber and the other surface being exposed to said intermediatechamber, whereby the pressure differential between said inlet andintermediate chambers urges said regulator valve means in a direction toseal said second passageway.

References Cited by the Examiner UNITED STATES PATENTS 2,915,084 12/1959Taylor 13750l 3,020,891 2/1962 Jaseph 91446 X 3,020,892 2/1962 Arbogast91-446 3,125,319 3/1964 Arbogast 9l47 X MARTIN P. SCHWADRON, PrimaryExaminer.

SAMUEL LEVINE, Examiner.

P. T. COBRIN, B. L. ADAMS, Assistant Examiners.

3. A CONSTANT SPEED LOWERING CONTROL MEANS FOR A HYDRAULIC ELEVATORSYSTEM INCLUDING A JACK CYLINDER CONTAINING HYDRAULIC FLUID, AN ELEVATORCAR PLUNGER RECIPROCABLE THEREIN, A PUMP AND A RESERVOIR, COMPRISING AVALVE CASING INCLUDING AN INLET CHAMBER, AN INTERMEDIATE CHAMBER AND ADISCHARGE CHAMBER, SAID INLET CHAMBER BEING IN CONTINUOUS COMMUNICATIONWITH SAID INTERMEDIATE CHAMBER THROUGH A FIRST PASSAGEWAY OF VARIABLEEFFECTIVE SIZE AND SAID INTERMEDIATE CHAMBER BEING IN SELECTIVELYCONTROLLABLE INTERMITTENT COMMUNICATION WITH SAID DISCHARGE CHAMBERTHROUGH A SECOND PASSAGEWAY, AN INLET PORT IN SAID CHAMBER ADAPTED TO BECONNECTED TO THE JACK CYLINDER OF A HYDRAULIC ELEVATOR SYSTEM WITH WHICHTHE CONTROL MEANS IS ADAPTED TO BE USED, A DISCHARGE PORT IN SAIDDISCHARGE CHAMBER ADAPTED TO BE CONNECTED TO THE RESERVOIR OF AHYDRAULIC ELEVATOR SYSTEM, SELECTIVELY OPERABLE SPEED CONTROL VALVEMEANS DISPOSED IN SAID FIRST PASSAGEWAY FOR CONTROLLING THE VARIABLEEFFECTIVE SIZE THEREOF, SAID CONTROL VALVE MEANS HAVING TWO OPERATIVEPOSITIONS CORRESPONDING TO TWO LOWERING SPEEDS OF AN ELEVATOR CARPLUNGER WITH WHICH THE CONTROL MEANS IS ADAPTED TO BE USED, REGULATORVALVE MEANS DISPOSED IN SAID SECOND PASSAGEWAY FOR REGULATING FLUID FLOWTHEREIN, SAID REGULATOR VALVE MEANS INCLUDING PRESSURE RESPONSIVE MEANSASSOCIATED THEREWITH ADAPTED TO SELECTIVELY SEAL SAID SECOND PASSAGEWAYAGAINST HYDRAULIC FLUID FLOW FROM SAID INTERMEDIATE CHAMBER TO SAIDDISCHARGE CHAMBER TO INTERRUPT COMMUNICATION THEREBETWEEN, ANDPOSITIONING MEANS COUPLED TO SAID REGULATOR VALVE MEANS AND SENSITIVE TOTHE PRESSURE DIFFERENTIAL BETWEEN SAID INLET AND INTERMEDIATE CHAMBERSFOR ADJUSTING SAID REGULATOR VALVE MEANS TO PROVIDE A PRESSURE IN SAIDINTERMEDIATE CHAMBER SUCH THAT THE PRESSURE DIFFERENTIAL BETWEEN SAIDINLET AND INTERMEDIATE CHAMBERS REMAINS SUBSTANTIALLY CONSTANT UNDERVARYING PRESSURE CONDITIONS IN SAID INLET CHAMBER.